Field of the Invention
The present invention is generally directed to treating exhaust gas streams and is more particularly directed to systems and methods for removing particulate matter from exhaust gas streams.
Description of the Related Art
An electrostatic precipitator (ESP) is a large, industrial emission-control unit. An ESP is designed to trap and remove dust particles from the exhaust gas stream of an industrial process. ESPs are used in a wide variety of industries including power/electric generation, cement manufacturing, chemical manufacturing, metal manufacturing, and paper production.
In many industrial plants, particulate matter created in the industrial process is carried as dust in the hot exhaust gases. These dust-laden gases pass through an ESP that collects most of the dust. Cleaned exhaust gas then passes out of the precipitator and through a stack to the atmosphere. Electrostatic precipitators typically collect 99.9% or more of the dust from the exhaust gas stream.
ESPs operate by electrostatically charging the dust particles in the exhaust gas stream. The charged particles are then attracted to and deposited on plates or other collection devices. When enough dust has accumulated, the collectors are shaken to dislodge the dust, causing it to fall with the force of gravity to hoppers below. The dust is then removed by a conveyor system for disposal or recycling.
Depending upon dust characteristics and the gas volume to be treated, there are many different sizes, types and designs of electrostatic precipitators. Very large power plants may have multiple electrostatic precipitators for each unit.
During electrostatic precipitation, six activities typically take place: 1) Ionization—Charging of particles; 2) Migration—Transporting the charged particles to the collecting surfaces; 3) Collection—Precipitation of the charged particles onto the collecting surfaces; 4) Charge Dissipation—Neutralizing the charged particles on the collecting surfaces; 5) Particle Dislodging—Removing the particles from the collecting surface to the hopper; and 6) Particle Removal—Conveying the particles from the hopper to a disposal point
The major ESP components that accomplish these activities include Discharge Electrodes; Power Components; Precipitator Controls; Rapping Systems; Purge Air Systems; and Flue Gas Conditioning
The complexity of ESP and the requirement for a large number of components makes the ESP process complicated and unreliable. Thus, there is a need for a simpler, more effective and more economical system for removing particles from an exhaust gas stream.
Thus, there remains a need for improved systems for removing particulate matter from exhaust gas streams.